Photgraphic layers and their preparation



United States Patent 3,287,134 PHOTOGRAPHIC LAYERS AND THEIR PREPARATION Paul Kainrath, Langen, Giinther Herbert, Sprendlmgen,

and Heinz Schiller, Langen, Germany, assrgnor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware No Drawing. Filed Mar. 9, 1964, Ser. No. 350,529

8 Claims. (CI. 96-77) This invention relates to photographic layers, and more particularly to silver halide emulsion layers, having dispersed therethrough lipophile compounds especially lipohile color formers.

The present application is a continuation-in-part of copending application Ser. No. 204,084 filed June 21, 1962 (now abandoned).

It has previously been suggested in the art to dissolve lipophile compounds, and in particular color formers or couplers, in suitable solvents and then, if necessary, in the presence of a wetting agent, to disperse the solution in aqueous gelatin. The dispersions thus formed are then added to the light-sensitive silver halide emulsions or other layer forming solutions prior to the pouring of the solutions to form the layer. Phthalic acid esters or phosphoric acid esters have been suggested in the prior art as suitable solvents. Other solvents, for the same purposes, have been described in hte literature as, for example, in U.S. Patents 2,322,027 and 2,533,514. However, it is well known that many color formers or couplers are not sufiiciently soluble in the prior art solvents. From a practical point of view, this means that once the compounds have been incorporated into the layers, they crystallize within the photographic layers, thus causing opalescence or turbidity therein. Further, in the case of coupling components, the color images formed during the color development usually have insufficient color density due to the crystallization referred to, as the oxidation products of the developing agents do not react sufficiently with the crystallized couplers or color formers. This effect is, of course, highly undesired and is particularly pronounced in the event that the material, prior to the processing, is stored for prolonged periods at low temperatures. The shelf life of layers containing lipophilic color formers and made by prior art processes is, therefore, relatively short. With a view to obtaining high color density in thin layers, it is desirable that the ratio solvent to color former be as small as possible. In general, the weight ratio of the glyceryl ester to lipophile compound will be 1:1 to 1:3. For this reason, the undesired crystallization referred to cannot be obviated by increasing the amount of the solvents previously used.

Because of the difliculties referred to, it has previously been suggested to employ both a high boiling solvent and a low boiling auxiliary solvent, thereafter the low boiling auxiliary slovent is evaporated upon dissolution of the lipophile compound. According to another suggestion to overcome the drawbacks of the prior art solvents, two separate dispersions are prepared, that is, a first dis persion of the coupler which is free of solvent and a second dispersion which consists solely of the high boiling solvent. Both dispersions are then admixed with the light-sensitive emulsion in a desired predetermined ratio. The two last-mentioned processes, however, are relatively complicated as they require additional working steps and for this reason these processes have not been adopted by the industry and have not met with success.

It is known by those versed in color photography that color former-containing layers generally have the tendency to occlude a portion of the silver formed during 3,287,134 Patented Nov. 22, 1966 "ice the development of the exposed layers. This is an extremely undesirable effect which is particularly pronounced in the presence of the prior art solvents. This occlusion phenomenon, of course, has the elfect that in the bleaching bath the occluded silver is not converted into a soluble salt. This, in turn, means that the layer, after the bleaching, still contains traces of metallic silver and for this reason, developed layers have a yellowish turbidity.

It is a primary object of this invention to overcome the disadvantages of solvents used in accordance with the prior art for dissolving lipophilic compounds, and in particular couplers or color formers, and to provide a solvent which readily dissolves the lipophile compounds and can be incorporated into photographic layers in a simple and rapid manner.

Another object of this invention is to provide for a process of preparing lipophile compound-containing pho-. tographic layers which is simple to carry out and results in photographic layers of superior quality.

Generally, it is an object of this invention to improve on the art of color photography and color layers as presently practiced.

According to the present invention, water-permeable colloid layers of photogrpahic elements have dispersed therethrough (1) A lipophile organic photographic adjuvant compound containing at least one aliphatic carbon chain of at least 5 carbon atoms and being selected from the group consisting of:

(a) Color formers capable of forming upon chromogenic development of exposed silver halide grains with a primary aromatic amine color developing agent a dye selected from the group consisting of quinoneimine and azomethine dyes,

(b) Light-filter dyes capable of absorbing light in the visible and ultraviolet regions of the spectrum,

(0) Antioxidants capable of reducing the oxidation of latent silver images; and

(2) A triglyceride of mixture of long chain aliphatic monocarboxylic acids have at least 8 carbon atoms and being liquid at C. The preferred triglycerides or glyceryl esters are preferably naturally occurring fats in a pure or refined form.

The photographic colloid layers, e.g., gelatino-silver halide emulsion layers, can be prepared readily (l) by uniformly mixing the lipophile compound with the glyceryl ester, for instance, by dissolving the lipophile compound in the glyceryl ester, (2) by uniformly admixing the resulting uniform mixture of the lipophiliccompound and glyceryl ester with an aqueous dispersion of a waterpermeable, macromolecular organic colloid binding agent, and (3) by coating the resulting dispersion as a layer onto a suitable surface forming a photographic layer.

The mixing of the lipophile compound and the glyceryl ester can be accomplished easily when the ester is in the liquid state by simple stirring or by mixing in a high-speed liquid blending mixer. A colloid mill or homogenizing apparatus can be used, especially with solid fats or glyceryl esters. The admixture of the lipophile compound and glyceryl ester can be mixed with the aqueous water-permeable colloid in like manner.

In the preferred and most important aspect of the invention, lipophile color formers are used. Such color formers are well known in the prior art and are free from ionizable groups, e.g., carboxylic and sulfonic groups. Suitable such color formers are described in the patents that are referred to above and in the following U.S. Patents: 2,298,443, 2,343,702, 2,369,489, 2,474,293, 2,521,- 908, 2,600,788, 2,725,291, 2,933,391. These color formers are of high molecular weight, essentially colorless and contain as an active dye-forming or color-former nucleus a structure of the formula:

where is a member selected from the group consisting of Suitable light-filter lipophile dyes are described in US.

Patent 2,186,731 and suitable lipophile antioxidants are described in U.S. Patents 2,732,300, 2,728,659 and 2,835,579.

Any water-permeable macromolecular colloid binding agent can be used in making the colloid layers of the invention. Thus, in addition to the gelatin of the following examples one can use mixtures of gelatin and dextrin, dextran or polyvinyl pyrrolidone; polyvinyl alcohol; agaragar, polyglycuronic acid or other neutral or synthetic colloids that are useful as binding agents for silver halide grains. With this invention, any glyceryl esterof a higher fatty acid can be used. For example, it has been ascertained that lard lends itself particularly well as solvent for lipophile compounds. Lard and the other glyceryl esters of fatty acids have an excellent solvent capacity with regard to lipophile compounds or couplers. Couplers which have been dispersed while dissolved in the inventive solvent do not crystallize even upon prolonged storage at exceedingly low temperatures and the silver occlusion referred to is largely prevented.

From a practical point of view, it has been established that natural fats, preferably in refined or purified form, are particularly suitable. As previously mentioned, lard (hog fat) gives excellent results.

Applicants do not wish to be limited by any theories advanced by them, but it' is believed that the excellent results obtained with naturally occurring fats are predicatedon the fact that these fats contain only a minor percentage of low molecular weigh fatty acids.

As previously mentioned, it is advantageous to refine or purify the fats prior to their employment as a solvent. For this purpose, the fats may be. dissolved in a suitable solvent, thereafter the solution is washed with water or diluted salt solution and is then treated with adsorbing agents. The solvent is then removed by distillation. In choosing the particular solvent, care should be taken that a solvent is used which, upon distillation, does not leave residues which could adversely affect the photographic emulsion. The ethyl ester of acetic acid may be mentioned asa suitable solvent.

Further, it is within the scope of this invention to disperse in conjunction with the lipophile compounds, other suitable emulsion adjuvants, e.g. filter dyes, oxidation protecting agents, and the like, which thus, by means of the glyceryl esters, are dispersed in the layer-forming solutions.

It is also possible to disperse the lipophile compounds and, if desired, additional agents, on the one hand, and the glyceryl esters of mixtures of higher fatty acids and, if desired, additional solvents, on the other hand, in the layer-forming solutions.

The invention will now be described by examples, it being understood, however, that these examples are given ,by way of illustration and not by way of limitation and that many changes may be effected without affecting in any way the scope and spirit of this invention as recited in the appended claims.

acid octadecyl amide were dissolved in 6 grams of re fined lard at a temperature of 50 C. The solution thus obtained was admixed with cm; of a 5% inert gelatin which contained 0.3 gram of Hostapon T (Trademark). This mixture thus obtained was agitated at a temperature of 50 C. in a homogenizer for about ten minutes whereafter, while still agitating, the mixture was cooled at a temperature of 30 C.

(B) As control, a dispersion was prepared in the same manner as under A, but the solvent in this instance was not lard but an equal amount of phthalic acid dibutyl ester.

Preparation 0 coupler-containing photographic layers 40 gramsof'coupler dispersion A was added to 100 cm. of a silver halide gelatin emulsion. The emulsion was thereafter poured onto a film base or carrier to form a layer in the usual manner and dried. A second layer was prepared in the same manner from 40 grams of dispersion B.

Development The two light-sensitive layersA and B thus obtained were exposed with a gray wedge and were then subjected in known manner to a color reversing development. The color developer 'had the following composition:

Water liter 1 Hydroxylamine-hydrochloride gram 1.5 Z-amino-S-diethylaminetoluene hydrochloride do 2.5 Anhydrous sodium sulfite do 2.0 Anhydrous potassium carbonate do 100 Potassium bromide do 0.5

The bleaching bath had the following composition:

Water r 1 Potassium ferricyanide grams Potassium bromide do 50 Sec. Sodium phosphate do 10 The film samplewhich included the coupler dispersion A, that is, the dispersion prepared with lardas solvent, had a clear appearance, while the film sample containing the coupler dispersion B prepared with phthalic acid dibutyl ester exhibited a yellowish turbidity. This turbidity. was determined to consist of residual silver and could be removed by prolonged treatment with a 1% potassium cyanide solution.

EXAMPLE II Example I was repeated, but the film strips, prior to exposure and development, were stored for seven days.-

It was determined that the at a temperature of 0 C. color density of the film sample A,,that is, the sample. containing the lard, was the same as that of Example I.

By contrast, the color density of sample B 'had dropped considerably.

EXAMPLE III-A Instead of 4.5 g. of hardened coconut oil of Example IIL-A, 4.5 g. of pure olive oil are used.

After thoroughly admixing the coupler dispersions of Example III-A and B with a silver bromide-iodide emulsion (97 mol percent bromine, 3 mol percent iodine),

forming an emulsion layer, exposure to light through .a gray wedge and negative color development with the use 1 Oleic acid methyl 'tauride sodium salt.

Four and one-half grams each of the yellow coupler alpha benzoyl 2 [N methyl N octadecylamino] acetanilide are dissolved on the steam bath in (a) 4.5 g. of solidified coconut oil (b) 4.5 g. of pure olive oil (c) 4.5 g. of pure cocoa butter and dispersed as indicated in Example II. After admixture with a suitable silver-bromide-iodide emulsion with a content of 98 mol percent of bromine and 2 mol percent of iodine, forming a layer of emulsion, exposure of the layer through a gray wedge and color reversal development with the use of 4-amino-N-ethyl-N-(betamethane sulfonamidoethyl) m toluidine sesquisulfatemonohydrate as a color developer substance, excellent yellow dye pictures for color reversal processes are obtained.

EXAMPLE V Four and one-half grams of purple coupler S-octadecylamido 1 (2',4,6' trichlorophenyl) 5 pyrazolone are dissolved at 70 C. in 13.5 g. of solidified coconut oil and 13.5 ml. of ethyl acetate. The solution is added to 100 cc. of a 7.5% gelatin solution which contains 0.9 g. of the oleic acid methyl tauride sodium salt emulsifying agent, and stirred for min. at 40 C. with a homogenizing machine.

The solidified coupler dispersion is formed into noodleshape and washed for about 3 hrs. with cold water to remove the ethyl acetate. After admixing thoroughly with a suitable aqueous silver-hromide-iodide emulsion which contains 98 mol per cent bromine and 2 mol per-- cent iodine, coating to form an emulsion layer, exposure of the layer to light, with a gray wedge and color reversal development, with the use of 4-amino-N-ethylN-(beta methane sulfonamidoethyl) m toluidine sesquisulfatemonohydrate as color developer substance, a magenta dye picture excellent for color reversal processes is obtained.

EXAMPLE VI (a) Four and one-half grams of 3-heptadecyl-1- (2',4',6 trichlorophenyl) 5 pyrazolone, a purple color former, are dissolved at 50 C. in 13.5 g. of hydrogenated coconut oil. The solution is added to 100 cc. of a 7.5% aqueous gelatin solution which contains 0.9 g. of oleic acid methyltauride as sodium salt, and stirred for 10 minutes at 50 C. with a homogenizing machine.

(b) Instead of 0.9 g. of oleic acid/methyl tauride sodium salt of Example V, 0.9 g. of dodecylsulfate'sodium salt is used.

After thoroughly admixing the coupler dispersions (a) and (b) with a suitable aqueous silver bromide-iodide emulsion containing 98 mole percent bromide and 2 mole percent iodide, forming an emulsion layer, exposure of the layer to light with a gray wedge and color reversal development with the use of 4-amino-N-ethyl-N-betamethane sulfonamidoethyl m toluidine-sesquisulfate monohydrate as color developer substance, a purple dye picture excellent for color reversal processes is obtained.

EXAMPLE VII Four and one-half grams of the ultraviolet absorber 2-hydroxy-4-octyloxybenzophenone are dissolved at 60 C. in 9 g. of solidified coconut oil. The solution is added to 100 cc. of a 7.5 gelatin solution which contains 0.7 g. of oleic acid-methyl tauride-sodium salt, and admixed 10 minutes at 40 C. with a homogenizing machine. The substance dispersion is coated in the usual manner on a cellulose tniacetate base and dried, in which case a clear film is obtained. The ultraviolet absorption of such an individual layer is the same prior to and after passing through a color reversal developing process, i.e., the active material is incorporated in the layer in a manner resistant to ditfusion.

EXAMPLE VIII Four and one-half grams of Z-n-octadecylhydroquinone are dissolved at 40 C. in 9 g. of solidified coconut oil. The solution is added to 100 cc. of a 7.5% aqueous gelatin solution which contains 0.7 g. of oleic acid methyltauride-sodium salt, and stirred :for 10 minutes at 40 C. with a homogenizing machine. This solution is then added to an aqueous gelatin solution and the latter formed into a layer of a photographic element that requires the presence of a non-diffusing antioxidant.

Results similar to those :given in the foregoing Examples I-VI can be obtained by substituting for the lipophile color formers thereof in equivalent amount other lipophile color formers that are described in the patents given above including l-hydroxy-Z-naphthoic acid-octadecylamide, l-hydroxy-Q-naphthoic acid dodecycloxypropyl amide, N-(1-hydroxy-2-naphthoyl)-N'-[2,4-bis- (1,1 dimethylpropyl)phenoxyacetyl] 1,2-ethylenediamine; 1-phenyl-3-heptadecylpyrazolonc-5 and the corresponding 2-chlorophenyl and 2,4',6'-trichlorphenyl compounds; 3-alpha-[2,4-bis(1,l dimethylpropyl)phenoxy]-n-butyramido-1 (2',4,6' 4 trichlorphenyD-pyrazolone-5 and 3-[4(l,l-di1nethylpropyl) -phenoxy1-aoetarmido-1-(2,4',6'-trichlorphenyl)pyrazolone-S.

In addition to the important advantages of the invention given above, the invention has the advantage that it is simple to carry out and utilizes readily available glyceryl esters of higher aliphatic acids.

While specific embodiments of the invention have been described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

We claim:

1. A photographic element having a light-sensitive silver halide layer and comprising at least one waterpermeable, macromolecular organic colloid layer having dispersed therethrough (1) a lipophile organic photographic adj uvant compound containing at least one aliphatic carbon chain of at least 5 carbon atoms and being selected from the group consisting of:

(a) color formers capable of forming upon chromogenic development of exposed silver halide grains with a primary aroma-tic amine color developing agent a dye selected .from the group gonsisting of quinoneimine and azomethine (-b) light-filter dyes capable of absorbing light in the visible and ultraviolet regions of the spectrum,

(c) antioxidants capable of reducing the oxidation of latent silver images; and

(2) a triglyceride of a mixture of long chain aliphatic monocarb'oxylic acids of at least 8 carbon atoms and being liquid at C.

2. An element according to claim 1 wherein said colloid layer is a gelatin-containing layer.

3. An element according to claim 1 wherein said colloid layer is a gelatino-silver halide emulsion layer.

4. An element according to caim 1 wherein said trigycen'de is .a naturally occurring fat.

5. An element according to claim 1 wherein said triglyceride is lard.

6. A photographic element having at least one gelatinosilver halide emulsion layer containing (1) color former having at least one aliphatic carbon chain of at least 5 carbon atoms capable of forming upon chromogen-ic development of exposed silver 7 halide grains a dye selected from the group consisting of quinoneimine vand azomethine dyes, and (2) -a triglyceride of a mixture of long chain aliphatic monocarboxylic acids of at least 8 carbon atoms and being liquid at 90 C.

7. An element according to claim 6 wherein said tniglyceride is a naturally occurring fat.

8. An element according to claim 6 wherein said triglyceride is lard.

V 8- References Cited by theExaminer UNITED STATES PATENTS 6/1943 Jelley et al. 96-97 2/1945 Knott 96-97 

1. A PHOTOGRAPHIC ELEMENT HAVING A LIGHT-SENSITIVE SILVER HALIDE LAYER AND COMPRISING AT LEAST ONE WATERPERMEABLE, MACROMOLECULAR ORGANIC COLLOID LAYER HAVING DISPERSED THERETHROUGH (1) A LIPOPHILE ORGANIC PHOTOGRAPHIC ADJUVANT COMPOUND CONTAINING AT LEAST ONE ALIPHATIC CARBON CHAIN OF AT LEAST 5 CARBON ATOMS AND BEING SELECTED FROM THE GROUP CONSISTING OF: (A) COLOR FORMERS CAPABLE OF FORMING UPON CHROMOGENIC DEVELOPMENT OF EXPOSED SILVER HALIDE GRAINS WITH A PRIMARY AROMATIC AMINE COLOR DEVELOPING AGENT A DYE SELECTED FROM THE GROUP CONSISTING OF QUINONEIMINE AND AZOMETHINE DYES, (B) LIGHT-FILTER DYES CAPABLE OF ABSORBING LIGHT IN THE VISIBLE AND ULTRAVIOLET REGIONS OF THE SPECTRUM, (C) ANTIOXIDANTS CAPABLE OF REDUCING THE OXIDATION OF LATENT SILVER IMAGES; AND (2) A TRIGLYCERIDE OF A MIXTURE OF LONG CHAIN ALIPHATIC MONOCARBOXYLIC ACIDS OF AT LEAST 8 CARBON ATOMS AND BEING LIQUID AT 90*C. 